Persons located behind glazing units, such as office workers in buildings with an outer glass structure, are vulnerable to the effects of a bomb blast. Bomb blasts may result in injuries or fatalities.
Persons may be killed with fragments from a bomb casing or the body of a car containing such a bomb. Material in close contact with explosive material from, for example, a terrorist vehicle bomb, will travel at very high velocity, and in many cases, the resulting fragments may be travelling at a speed greater than a bullet. A person hit with such a fragment from a bomb casing or a body of a car, is therefore being hit with fragments with the similar effect to that of a large bullet. Clearly, this results in serious injury or fatality.
On activation of a bomb, debris may also be formed from the resulting break-up of a car filled with explosive material. Debris may result from the break-up of a car body and engine etc. Generally, the velocity of such debris is much lower than the previously described fragments. However, the mass of such debris is generally greater than that of fragments, rendering the formed debris extremely dangerous. The debris can therefore result in serious injury or fatality.
A bomb blast may also result in eardrum rupture of persons in close proximity to a bomb. Blast over-pressure resulting from an explosion may cause eardrums to rupture, resulting in permanent loss of hearing.
A bomb blast may also result in lung damage, as when a person is hit by blast over-pressure, a shockwave travels through a person's body. If the shockwave is of sufficient intensity, this can rupture blood vessels in the lungs, resulting in serious injury or more likely fatality due to inability to breath. The blast pressure required to cause lung damage is generally greater than that needed to cause eardrum rupture.
A bomb blast may also result in persons being thrown around. This may also lead to injuries which may be fatal.
A further major hazard with bomb blasts, is that caused by glass in glazing units. This is of great concern in many office blocks which have an outer structure mainly formed of glass or have significant areas of glass. The resulting blast over-pressure from an explosion may cause the shattering of glazing, resulting in the projection of lethal glass shards. The glass shards can be projected at speeds up to or even greater than 100 meters per second (i.e. over 200 miles per hour). Glass shards are considered potentially lethal at speeds of over 9 meters per second (i.e. 20 miles per hour). At lesser speeds persons may suffer moderate or serious injuries. It has been found that most injuries from a bomb blast targeted at an office block, will be caused by glass shards. In a bomb blast situation, glass is projected from a window primarily perpendicular to the plane of the window i.e. with very little spread regardless of bomb location. Glazing fragments will initially take a primarily horizontal path, thereafter falling due to gravity. This results in the lethal nature of the glass shards.
Secondary debris may also be generated by the bomb explosion. The secondary debris may be formed by dislodged/projected items moved by the effects of the explosion. Secondary debris can cause serious injury to occupants of a building. Secondary debris may be formed from suspended ceiling tiles (dislodged by the blast and falling due to gravity), light fittings, lightweight stud partitions, furniture, masonry partitions and non-glazed external cladding.
A bomb blast may also result in the complete structural collapse of a building. In the event that a structure collapses, occupants within such a structure may be crushed to death.
Although a number of protective chairs exist such as described in U.S. Pat. Nos. 5,164,536, 5,448,938, 6,164,181, 6,688,554, FR 2803256, and JP 2005,043030, which are incorporated herein by reference, none of these chairs relate to protecting an occupant in the event of a bomb blast.
The present invention provides a cost effective way of protecting an occupant of a building exposed to a bomb attack. Although toughened glass and laminated glass have previously been used to protect occupants from bomb blast, these types of glasses are expensive thereby substantially increasing the cost of construction. Moreover, although locating protective films over annealed and toughened glass may also be considered, using such types of glass films create their own problems. For example, protective films suffer from the following disadvantages: limited protection; limited design life; difficult to install to obtain full benefits; need for special measures to prevent damage and deterioration due to cleaning; easily damaged detracting from the films aesthetic qualities; and expense. Additionally, such types of films can cause a whole glass pane to be blasted into a room which is highly dangerous. Toughened glass also tends to break into large blocks, which are extremely dangerous. Moreover, energy resulting from a bomb blast which is transmitted to glass, will as a result of filming be transmitted to a building possibly resulting in catastrophic failure of the building.
It is an object of at least one aspect of the present invention to obviate or mitigate at least one or more of the aforementioned problems.
It is a further object of at least one aspect of the present invention to provide a chair which assists in the protection of an occupant so that the probability of a person surviving a bomb blast or similar explosive event is increased.
It is a further object of at least one aspect of the present invention to provide a chair which is capable of protecting surrounding workers in an office environment when a bomb explodes.